Low temperature alloying of Cu and Ni nanoparticles formed within thermally evaporated fatty acid films

The low temperature alloying of copper and nickel nanoparticles synthesized in a fatty acid film by a novel ion-entrapment process is described. Nanoparticles of copper and nickel were grown in thermally evaporated stearic acid films by immersion of the film sequentially in solutions containing Cu2+ ions and Ni2+ ions followed by their in-situ reduction at each stage. Entrapment of Cu2+ and Ni2+ ions in the stearic acid film occurs by selective electrostatic binding with carboxylate ions in the fatty acid matrix. Thermal treatment of the stearic acid-(Cu + Ni) nanocomposite film at 100 °C resulted in the formation of a Cu-Ni alloy. The process of Cu2+ and Ni2+ ion incorporation in the stearic acid matrix and synthesis of the Cu-Ni alloy were followed by quartz crystal microgravimetry (QCM), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD)

Multilayer Langmuir-Blodgett assemblies of hydrophobized CdS nanoparticles by organization at the air-water interface

The formation of multilayer Langmuir-Blodgett (LB) films of hydrophobized CdS nanoparticles by organization at the air-water interface is described. The hydrophobization of CdS nanoparticles (60 Å diameter) synthesized in an aqueous medium is accomplished by extraction of the particles from solution into thermally evaporated octadecylamine (ODA) films. Vigorous stirring of the ODA-CdS nanocomposite films in organic solvents resulted in dispersion of the CdS particles in the organic phase. The hydrophobic CdS nanoparticles were dispersed on the surface of water, organized into a fairly closely packed monolayer and multilayer films formed on different substrates by the versatile Langmuir-Blodgett technique. The organization of the particles and formation of multilayer films by the Langmuir-Blodgett technique was followed by surface pressure-area isotherm measurements of the nanoparticle Langmuir monolayer, quartz crystal microgravimetry, contact angle measurements, UV-vis spectroscopy and Fourier transform infrared spectroscopy studies. It is observed that a reasonably close-packed monolayer of the CdS nanoparticles forms on the surface of water and that excellent multilayer films of the particles can be grown on different supports via sequential transfer by the LB technique

Crystallization of SrCO<SUB>3</SUB> within thermally evaporated fatty acid films: unusual morphology of crystal aggregates

Reaction of CO2 with electrostatically entrapped Sr2+ ions within thermally evaporated stearic acid films leads to the in-situ growth of SrCO3 crystals in highly organized assemblies, the organization possibly occurring due to hydrophobic association of the crystallites covered by a monolayer of stearic acid

Intermetallic phase transformations during low-temperature heat treatment of Al/Ni nanoparticles synthesized within thermally evaporated fatty acid films

The phase evolution during low-temperature heat treatment of Al and Ni nanoparticles synthesized within thermally evaporated fatty acid films is described. Nanoparticles of aluminum and nickel were grown in thermally evaporated stearic acid (StA) films by immersion of the film sequentially in solutions containing Al3+ and Ni2+ ions followed by in-situ reduction of the metal ions to yield nanoparticles of Al and Ni of ca. 230 Å diameter within the fatty acid matrix. Thermal treatment of the StA - (Al + Ni) nanocomposite film at 100 °C resulted in the formation of a metastable η phase, Al9Ni2, which on further heating at 125 °C decomposed to form Al3Ni2

Synthesis of Au-core/Pt-shell nanoparticles within thermally evaporated fatty amine films and their low-temperature alloying

The low-temperature alloying of bimetallic Au-Pt nanoparticles entrapped within thermally evaporated fatty amine films by a novel ion-exchange technique is described. Nanoparticles of gold and platinum were grown in thermally evaporated octadecylamine films by immersion of the film sequentially in solutions containing AuCl4− ions and PtCl62− ions followed by their in situ reduction at each stage. Entrapment of AuCl4− and PtCl62− ions in the octadecylamine (ODA) film occurs by selective electrostatic binding with the ammonium ions in the fatty amine matrix. This process leads to the formation of a Au-core/Pt-shell structure of the nanoparticles within the lipid matrix. Thermal treatment of the ODA-(Au-core/Pt-shell) nanocomposite film at 150 °C resulted in the formation of a Au-Pt alloy. The process of AuCl4− and PtCl62− ion incorporation in the ODA matrix and synthesis of the Au-Pt alloy were followed by quartz crystal microgravimetry, Fourier transform infrared spectroscopy, UV-vis spectroscopy, and X-ray diffraction measurements

Low temperature crystalline Ag-Ni alloy formation from silver and nickel nanoparticles entrapped in a fatty acid composite film

Nanoparticles of silver and nickel were grown in thermally evaporated fatty acid (stearic acid) films by immersion of the film sequentially in solutions containing Ag<SUP>+</SUP> ions and Ni<SUP>2+</SUP> ions. Attractive electrostatic interaction between the metal cations and the carboxylate ions in the fatty acid film leads to entrapment of the cations in the film. Thereafter, the metal ions were reduced in situ to yield nanoparticles of Ag and Ni of ~ 30 nm diameter within the fatty acid matrix. Thermal treatment of the stearic acid-(silver+nickel) nanocomposite films led to the formation of a Ni-Ag alloy at ~ 100°C. Prolonged heat treatment at this temperature resulted in the phase separation of the alloy and the reformation of individual Ag and Ni nanoparticles

Synthesis of nanoscale Fe-Ag alloy within thermally evaporated fatty acid films

The low-temperature alloying of Fe-Ag nanoparticles entrapped within thermally evaporated fatty acid films by a novel ion exchange technique is described. Nanoparticles of iron and silver were grown in thermally evaporated stearic acid (StA) films by sequential immersion of the film in solutions containing Fe<SUP>2+</SUP> ions and Ag<SUP>+</SUP> ions followed by their in situ reduction at each stage. Entrapment of Fe<SUP>2+</SUP> and Ag<SUP>+</SUP> ions in the StA film occurs by selective electrostatic binding with the carboxylate ions in the fatty acid matrix. Thereafter, the metal ions were reduced in situ to yield nanoparticles of Fe and Ag of ca. 35 nm diameter within the fatty acid matrix. Thermal treatment of the StA-(Fe + Ag) nanocomposite film at 200 °C resulted in the formation of an Fe-Ag alloy. Prolonged heat treatment at 250 °C resulted in the phase separation of the alloy and the re-formation of individual Fe and Ag nanoparticles. The process of Fe<SUP>2+</SUP> and Ag<SUP>+</SUP> ion incorporation in the StA matrix and synthesis of the Fe-Ag alloy were followed by quartz crystal microgravimetry, Fourier transform infrared spectroscopy, transmission electron microscopy and X-ray diffraction measurements